I. Field
The following description relates generally to wireless communications, and more particularly to uplink scheduling in wireless communication systems.
II. Background
Wireless communication systems are widely deployed to provide various types of communication; for instance, voice and/or data can be provided via such wireless communication systems. A typical wireless communication system, or network, can provide multiple users access to one or more shared resources. For instance, a system can use a variety of multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), Orthogonal Frequency Division Multiplexing (OFDM), and others.
Common wireless communication systems employ one or more base stations that provide a coverage area. A typical base station can transmit multiple data streams for broadcast, multicast and/or unicast services, wherein a data stream can be a stream of data that can be of independent reception interest to a mobile device. A mobile device within the coverage area of such base station can be employed to receive one, more than one, or all the data streams carried by the composite stream. Likewise, a mobile device can transmit data to the base station or another mobile device.
Generally, wireless multiple-access communication systems can simultaneously support communication for multiple mobile devices. Each mobile device can communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations.
Wireless communication systems oftentimes schedule downlink and uplink transmissions. As an example, base stations commonly assign channels, times, frequencies, and so forth for mobile devices to utilize for communicating over the uplink. Conventional uplink scheduling schemes are typically based upon power control algorithms. The goal of such algorithms can be to achieve sustainable transmit rates for all users in the system. For CDMA systems, the targeted rates for different users can usually be chosen to be substantially similar to one another; thus, the transmit power of each mobile device can be controlled such that the received signal-to-interference-and-noise ratio (SINR) exceeds a certain threshold. Such strategy can be more beneficial for utilization with voice-user oriented networks. For data networks, a framework that extends the power control algorithms to a more general rate-control framework can be employed where each user can target a different rate as long as the rate-vector is within a capacity region. Under this algorithm, the system can converge to a rate vector within the capacity region that can maximize a given utility function. However, the targeted rate vector remains sustainable in that every user transmits at every time and the algorithm leads to an equilibrium where every mobile transmits at a certain rate. Due to the existence of inter and intra cell interference, sustainable rates can introduce inefficiencies since such sustainable rates may not be the optimal achievable rates for the users.